When the bearing preload is applied, it is recommended to measure the deformation continuously....
When the bearing preload is applied, it is recommended to measure the deformation continuously. It should be pointed out that this kind of deformation is nonlinear. Increase the load at the high deformation stage at the low deformation stage, and increase the linear pretension load at the high deformation stage. There is a linear relationship between the main deformation and the load. The increase of preload will stop immediately, and constant stiffness can be obtained. Thereafter, there is a fixed relationship between the stiffness of axial and radial bearings, which is independent of external loads.
1、 Equipped with bearings, the bearing structure has a great impact on the bearing stiffness. Generally speaking, the outer ring of the centripetal thrust ball bearing and roller bearing has a large end face and has the ability to resist overturning torque for the bearing. When the temperature changes, the preload adjustment will not change much.
2、 Under the condition of allowable axial position, the support stiffness can be improved by multiple bearing supports and two or more radial bearing supports at each fulcrum. In recent years, axial preload and multiple sets of centripetal thrust bearings have been widely used in machine tool spindle assembly.
3、 In order to meet the requirements of Swedish bearing mating surface, better shape of shaft and seat hole and bearing installation position, position accuracy, lower surface roughness and higher bearing stiffness. Surface hardening is beneficial to improve hardness. Under the lubrication condition, press the extremely low hardness plug into and out of the seat hole several times, and there is certain interference, which is also beneficial to improve the bearing stiffness. If necessary, it is similar to using a clamping ring to handle the journal.
4、 The bearing preloading method can be used to improve the bearing stiffness. The bearing axial preload method can be used for ball bearings or bearings, while the radial preload method can be used for short cylindrical roller bearings, which can significantly improve the stiffness of the shaft. At this time, remove the bearing clearance or obtain a small negative clearance. However, when the speed is not too high and the temperature is not too high, adjust the negative clearance as small as possible.
These deformations can be observed, for example, by placing a probe on the surface of a bearing or on an appropriate part of a shaft with preload. The preloading method has the disadvantages of increasing bearing friction torque, increasing temperature rise, shortening service life, etc. It should be comprehensively considered, weigh the gains and losses, and select the appropriate preloading method.
